It is well known that in the fuel delivery system of an internal combustion aircraft engine, the carburetor produces an appropriate air/fuel mixture for delivery to the combustion chambers of the engine. The carburetor float maintains a predetermined level of fuel in a float bowl, which is positioned between the fuel inlet to the carburetor and the fuel discharge nozzle in the induction passage of the carburetor. The fuel level in the float bowl provides a uniform fuel head for the fuel discharge nozzle at the induction passage. Within the float bowl, the carburetor float is coupled to a needle valve in a pivoting relationship to control the level of fuel within the float bowl.
Typical prior art carburetor floats include metal thin-walled pontoons which are hollow and are intended to be liquid tight. A problem with these pontoons is that they malfunction when a leak develops and fuel seeps into the interior chamber of the pontoon. When this happens, the pontoon loses buoyancy and cannot function properly to control the fuel level in the float bowl. As a result, an improper air/fuel mixture is delivered to the combustion chambers of the engine. An improper air/fuel mixture adversely affects the performance of an aircraft engine and sometimes can lead to engine failure.
Hollow metal pontoons tend to leak at their joints where voids or imperfections are created during manufacture or by erosion.
Some metal pontoons are foam filled to provide strength for higher pressure fuel distribution systems. Other known carburetor floats include pontoons made from a solid foam plastic or other lightweight float material encased by a skin that is intended to be impervious to liquid. These foam-type pontoons, generally, are lighter than hollow metal pontoons.
At times, holes develop in the skin material. This allows fuel to enter the pontoon and "log" the foam body causing it to lose buoyancy.
Accordingly, it is an object of the present invention to provide an improved carburetor float that, if subject to a leak, will continue to function properly to control the level of fuel in the float bowl.
In addition, the present invention seeks to alleviate the excessive wear that occurs at the contact point between the float and the needle valve of the carburetor and at the pivot point of the carburetor.